Unless your food processor is huge, you’ll need to process this in a couple of batches. In the first, put half the watermelon, tomatoes and capsicum, and all the onion, chilli, garlic and ginger. Process this quite thoroughly, then transfer to a large bowl. Process the remaining watermelon, tomato and capsicum, this time leaving it a bit chunkier for texture. Then combine the two batches and stir well. Season to taste.
Refrigerate for an hour or so and serve chilled.
Dice the tomato and cucumber, slice the radish, and mix all ingredients together. Allow to sit for a few minutes for the flavours to make friends. Feel free also to add/substitute ingredients: avocado, edible flowers, dill would all be beautiful.
Just before serving, top the soup with the salad, heaping it into the middle. Add a final sprinkle of freshly cracked pepper. Bon appetit!